Contact persons or authors (primary investigators) of published studies are eligible for the study if (i) the study has been identified as probably or definitely fulfilling the criteria for inclusion in a Cochrane review, (ii) any information needed to complete the systematic review is missing from the published report, and (iii) a postal, or email, address is available for them. The reviewers should have completed assessment of studies for inclusion in the review and any data extraction.
The essential criterion for entry into First Contact is that the reviewer is uncertain how first contact should be made with the investigator in order to obtain missing information. In particular, the reviewer must be uncertain whether the experimental or the control intervention of First Contact will produce the best results. Thus, if the reviewer is confident that a particular approach (for example, a telephone call) should be used for a specific investigator, then that investigator should not be included in First Contact.
Reviewers may include investigators in the trial for whom previous contact attempts have yielded only a new postal, or email, address.
There is no minimum number of investigators with which a reviewer may participate in First Contact.
An investigator who is the contact person for more than one trial should be included only once by any particular reviewer. Should an investigator be randomised more than once by mistake, he or she will be treated as two separate investigators in the analysis (with appropriate sensitivity analyses).
